[Other] USUM - Directory help

I'm relatively new to the hacking community and I don't have too much space on my SD card, so I wanted to ask something: is there a way to find out where each piece of data is stored? Like, from video tutorials I know that Pokémon textures are stored in romfs/a/0/9/4 but is there an easy way to tell where all the other files are located? Like I said, I want to save space on my SD so I only want to grab the files I absolutely need. And I apologize if there's already something covering this topic but I've done some searching and haven't been able to find anything on it.